AB is a part of an electrical circuit (see figure). The potential difference "VA - VB", at the instant when current i=2 A and is…

Question

AB is a part of an electrical circuit (see figure). The potential difference "VA - VB", at the instant when current i=2 A and is increasing at a rate of 1 amp/second, is:

1. A. 5 volt
2. B. 6 volt
3. C. 9 volt
4. D. 10 volt (Correct answer)

Correct Answer

Option D — 10 volt

Detailed Solution & Explanation

The correct answer is 10 volt.

Key Points

• Traversing A to B across the inductor (1 H), the 5 V cell and the 2 $\Omega$ resistor: $V_A - L\dfrac{di}{dt} - 5 - iR = V_B$.
• Substituting $L=1$ H, $\dfrac{di}{dt}=1$ A/s, $i=2$ A, $R=2\,\Omega$: $V_A-(1)(1)-5-(2)(2)=V_B$.
• $V_A-V_B = 1+5+4 = 10$ volt.